1. Field of the Invention
The present invention relates to a semiconductor device.
2. Description of the Related Art
In recent years, a low resistance of a wiring resistance and a low dielectric constant of an interlayer insulation film have been promoted to improve a signal delay. Specifically, by changing a wiring material from Al to Cu, the wiring resistance is made to be a lower resistance. Besides, the interlayer insulation film is made to have a lower dielectric constant by applying a low dielectric constant insulating film (Low-k film) such as fluorine-doped SiO2, SiO2 film containing organic constituent, or an organic film instead of SiO2, and further by the porosity of the low dielectric constant film. However, the lowering of the dielectric constant of the interlayer insulation film causes a problem of a deterioration of heat conductivity on the other hand. In particular, the porosity brings about a thermal storage effect within the interlayer insulation film.
Meanwhile, the power consumption is increasing by a speeding up and a high integration density of a semiconductor device, and a heating value from inside of a semiconductor chip is more increasing.
From these circumstances, in the current semiconductor chip, a heating value increases and the heat tends to stay. Therefore, a heat release only from the rear surface of an Si substrate is not sufficient for the heat release, and thereby, it brings about a rise of a chip temperature, and it is possible to bring about an operation failure, and further, a reliability failure.
To solve these heat dissipation problems, a method to release the heat by bonding a metal plate or a metal fin on the rear surface of the Si substrate is suggested. However, the heat dissipation effect thereof is insufficient and more improvement is required.
A method to form multilayered dummy wirings in the semiconductor chip and connect the dummy wirings each other through dummy vias, and transmit the heat through the dummy wirings, to release the heat from the surface layer of a semiconductor chip, is suggested (for example, refer to Japanese Patent Application Laid-open No. Hei 10-199882). However, the surface layer of the semiconductor chip is generally sealed by a low heat conductive resin for avoiding a corrosion from environment and for protecting from a mechanical destruction. Therefore, also in this case, the heat remains in the semiconductor chip after all, and it is insufficient as a heat dissipation effect.